Impeller balancing and sealing device



puh 5 1927 H. F. BENSON IMPELLER BALANCING AND SEALING DEVICE Filed July 22. 1925 Illini! )Patented .lluly 5, 1927.

us` STATES Ldl? PATENT OFFICE.

HARRY F. BENSON, 0F HOLYOKE, MASSACHUSETTS, ASSIGNOR .T0 WORTHINGTON PUMP AND MACHINERY VIRGINIA.

CORPORATION, OF NEW YORK, N. Y., A CORPORATION 0F IMPELLER BALANCING AND SEALING DEVICE.

Application led July 22, 1925. Serial No. 45,189.

forms of balancing devices, and by which the balance will be maintained independently of wear through long service and be maintained independent of impeller speed or change in axial position of the impeller. The invention is applicable to either single or multistage pumps and for either horizontal or vertical service. It will, however be found of special value when applied to pumps of the deep well type, Where the great v depth and lift of water produces a heavy downward thrust unless balancing means are provided and where the impellers may be more or less inaccessible and consequently should require no adjustment or inspection after installation, and afford no opportunity for the deposit of sand'and foreign matter and consequent interference with operation. ln such pumps particularly, also, it is frequently necessary to produce a resultant up-l ward thrust to counteract the weight of the rotating parts aswell as the water load, and the devices embodying the present invention are well adapted for this purpose.

The invention includes broadly the use of axial flow means for producing the balance desired, as distinguished from the radial flow means heretofore suggested for this purpose, and certain features ofv construction and arrangement of parts all as fully de, scribed in the following specification vand specifically pointed out in the claims.

In the accompanying drawings forming a part of this specification, I have shown centrifugal and axial flow pumps embodying the invention in preferred forms, in which drawings- Figure 1 is a central vertical section of a horizontal centrifugal pump with my devices applied to secure a resultant thrust toward the back of the impeller; v

Figure2 is a similar view showing an impeller with the resultant thrust toward the suction or front of the impeller;

Figure 3 is a developed plan or edge vievvof the impeller of Fig. 1.

Referring nowto Fig. 1, A is the pump lcasing having the suction B and discharge volute C, and D is the impeller shown as of a common type. of centrifugal impeller with the hub 10. web 11. shroud 12 and impeller vanes 13,'the impeller being carried by the shaft E, which may be of any usual or suitable form.

As shown in Fig. 1, the impeller web 11 is provided at its periphery with inclined axially-extending slots 1 forming axial flow pumping vanes for liquid admitted to the back of the impeller from the suction through the usual' opening 2, and the shroud 12 is provided with similar inclined axial slots 3, the latter forming vanes on a projecting shoulder 4 coacting with an inwardly extending shoulder 5 on the casing to form axial flow pumping means and positioned to secure a partial balancing and the inner edge of the shroud 12 having sufficient clearance between it and the casing shoulder 6 for the admission of suction liquid vto the pumping slots 3. lVith this construc-` tion, the pressure on the back ofthe impeller web 11 will be suction pressure throughout, while the pressure on the outside of the shroud 12 will be at least discharge pressure from the slots 3 to the outer edge of the impeller, thus securing a resultant thrust on the impeller to the left in A Fig. l, which resultant thrust may be used for balancing pressure from other parts of the pump or for counteracting the weight of the rotating parts in a vertical pump.

In Figure 2 the construction is the same as in Fig. 1. except that the resultant thrust on the impeller by the position of the slots 3, is towards the suction, or to the right in Fig. 2, the slots 3 andco-acting shoulder 4 being placed on the web of the impeller, and the edge slots 1 being placed on the shroud 'of the impeller.

In the embodiment of my invention in any of the forms shown, or other suitable forms whichA may be used, the axial iiow pumping slots or vanes will be of such form and dimensions as to easily pump against the pressure at the impeller discharge, so as to maintain suction pressure on their inlet sides and prevent leakage of pressure fluid past the varies. The "valles or slots, however, are

as the fluid pumped by the balancing vanes is not a short circuit loss, but all this fluid is taken at suction pressure and raised to the impeller discharge pressure for delivery therewith, thus causing no loss, either in capacity or energy. Ity will be seen, also, that the balancing means is independent of the exact axial position of the impeller and allows a large axial range of position of the impeller, without affecting the efficient operation of the balancing devices, and that the operation of the devices `will not-be aftected by Wear through long service. It is not necessary, moreover, to accurately determine the area of the holes through the impeller web or the clearances between the impeller and casing through which the suction fluid is supplied to the balancing means, as these need only be large enough to supply l the maximum quantity of fluid to be pumped by the balancing means.. The value of the present improvementI as applied to' multistage pumps will also be apparent, as the provision of axial pumping vanes, as distinguished from radial vanes of prior balancing arrangements materially reduces not only the costv of assembly of pumps' generally in which the present improvement is present, but also avoids the large expense necessarily involved in multistage pumps when provided with radial vanes for a simi lar purpose, as there is no requirement for' accurate positioning of all the stages to se-f cure proper balancing and sealing.

What is claimed is: l. In a fluid pump,` the Combination with a casing and a rotating impeller therein producing fluid pressure at discharge, of sets of axial flow pumping vanes on opposite sides of the impeller cooperating with the casing to form axial flow pumping means arranged at diferent radialv distances to secure a resultant thrust on the impellerin'one direction.

2. In a uid pump, the combination with a casing and a rotating impeller therein producing pressure at discharge, of a set of axial flow pumping vanes on the exterior of one side ofthe impeller cooperating with the casing to form axial flow pumping means arranged to maintain suction pressure thereon, and a second set of axial flow pumping vanes carried by the exterior of the opposite side of the impeller cooperating with the casing to form axial flow pumping means arranged on a shorter radius to secure a resultant thrust on the impeller.

3. In a fluid pump, the combination with a casing. and a rotating impeller therein producing pressure at discharge, of a set of axial flow pumping vanes carried by the periphery of one side of the impeller and cooperating with'the casing to form axial flow pumping means, and a second set of axial flow pumping vanes carried by the exterior ot' the opposite side o the impeller cooperating with the casing to form axial ow pumping means arranged on a shorter radius to secure a resultant thrust on that side of the impeller.

Il. In a fluid pump, the combination with a casing, of ashrouded impeller, axial How pumping vanes carried by the web and shroud of the impeller and arranged to i pump from the side chambers of the impeller to the impeller discharge against discharge pressure, Huid connections for the supply of suction fluid to said chambers and axial flow pumping vanes, one' set of said axial flow pumping vanes being carried ati the outer periphery of the impeller and the other setvbeing carried on a shorter radius to secure a resultant thrust on the impeller in one` direction.

' In testimony whereof, Ihave hereunto set my hand.

HARRY F. BENSON. 

